The present invention relates to a device for dispensing a-fluid having bacteriostatic activity.
It is known to use heavy metals, such as silver, alloys thereof, or salts thereof as a substance having bacteriostatic or oligodynamic activity, i.e. a disinfectant for fluids. Silver is soluble in water at ppb concentrations, and silver ions delivered in this way act in bacteriostatic and bactericidal manner on germs that have penetrated into the fluid, thereby eliminating them.
Document EP-0 473 892 discloses a metering pump without air intake having an oligodynamic substance disposed at the admission valve of the pump chamber. Additionally, the oligodynamic substance may also be disposed in other parts of the metering pump. As described in document EP-0 473 892, the purpose of that device is to guarantee particularly effective elimination of germs. That purpose is achieved by providing prolonged contact between the liquid and the oligodynamic substance. By having said substance present at the inlet valve to the pump chamber, both the fluid contained in the pump chamber and a portion of the fluid contained in the tank is in permanent contact with the oligodynamic substance. This is further amplified if other portions of the pump, such as the pump chamber itself, or the outlet valve, include the oligodynamic substance.
That implementation suffers from a certain number of drawbacks. Thus, depending in the nature of the fluid contained in the receptacle, permanent contact between a portion of said fluid and the oligodynamic substance can give rise to problems of stability in said fluid during storage. Secondly, manufacture of the metering pump is made more complicated and thus more expensive if one or more component parts of the pump need to include an oligodynamic substance.
Document EP-0 580 460 discloses a fluid dispenser in which the bacteriostatic substance can be provided in the pushbutton on its own. Nevertheless, in that case, the effectiveness of the bacteriostatic activity can be limited, and depending on the configuration of the component parts of the pushbutton, some of the fluid expelled during actuation runs the risk of not coming into contact with the oligodynamic substance. Similarly, if storage time is relatively short, i.e. if the dispenser is reused quickly, a portion of the fluid remaining in the pushbutton between two successive actuations runs the risk of becoming contaminated. Also, if storage time between two successive actuations is long, then a non-negligible quantity of fluid is in permanent contact with the bacteriostatic substance, and that is undesirable.